Resonant explosion power unit with dilution air



G. FARNELL 2,502,291

RESONANT EXPLOSION POWER UNIT WITH DILUIION AIR July s, 1952 F1ed,.Dec16, 1947 HIS ATTORNEY.

Patented July 8, 1952 REsoNANT EXPLOSION POWER UNIT WITH DILUTION AraGeorge Farnell, Phillipsburg, N. J., assigner to Ingersoll-Rand Company,New York, N. Y., a corporation of New Jersey Application December 16,1947, Serial No. 792,071

l cooling air into the explosion chamber of the unit between successiveexplosionain such a manner that the cooling air will thoroughlyintermingle with the hot explosion gases in the chamber.'

Another object is to discharge explosion gases at practically constantpressure from the explosion chamber of a resonant power unit having asingle explosion zone.

Other objects will be in part obvious and in part pointed outhereinafter. Y

In the accompanying drawing in which simiar reference numerals refer tosimilar parts,

Figure 1 is a side elevationfofna gas turbine plant showing a resonantexplosion chamber constructed in accordance withthe practice of theinvention, l

Figure 2 is a transverse view of the resonant explosion power unit,somewhat enlarged, showing the position of the controlling devices whenat rest, and

Figure 3 is an enlarged sectional view of a detail of Figure 2.

Referring more particularly to the y drawing and at first to Figure-1,`a resonant explosion gas turbine plant, designated in general by 20, isshown as including a turbine 2 I, a resonant explosion power unit 22 forprovidingoperating gases for the turbine, and a compressor 23 driven bythe turbine for delivering vcompressed air to the power unit 22.

The compressor and turbine are shown as Vbeing of the axial flow typeshaving their rotors 24 and 25 coaxially arranged with each other and theopposed ends of their shafts 26 and 29 connected together by a coupling36. [On the other end of the shaft 29 is a power take-olf coupling 3land the outer end of the shaft Zllisy adapted to be connected with aclutch mechanism 32 which in turn is attached tothe operating shaft of astarting motor-33. Anoperating-leverarm 34 for the clutch mechanism 32is pivoted on the base of the starting motor to make possi-ble the Yengagement and disengagement of the clutch mechanism.

The resonant explosion powerunit 22 comprises a tubular casing 35 whichforms a chamber 36 having an explosion zone 31 located adjacent an endmember 38 of the casing 35, and a housing 39 shown as beingconcentrically arranged around the casing 35 to form an air supplychamber 40 therebetween. Compressed air is conveyed from 2 Claims. (Cl.60-39.65)

the compressor to the supply `chamber 40 by a conduit 4|, from whence apart of the air passes through a port 42 in the member 38 into theexplosion zone 31.

The flow of air through the port 42 is controlled by a pressureresponsive valve 43 shown as being of the poppet type and having itsstem 44 extending through an L-shaped projection 45 attached to the endmember 33 of the casing 35. The valve 43 is normally held unseated by aspring 46 encircling the valve stem and acting against the projection 45and the valve.

Fuel is injected into the compressed air in the explosion zone 31 by aspray nozzle 41, and the resulting explosive mixture is ignited by aspark plug 4B projecting through the housing 39 and into the casing 35in the transverse plane of the fuel spray nozzle. The fuel isconveyed tothe spray nozzle by a conduit 49 from a fuel pump 50 which may'itself'receive' fuel,l under pressure, through a main fuel line 5 I from-anoutside source (not shown).

Inorder to convey the exhaust gasesfrom'the explosion chamber 36 to theinlet of the turbine 2| a discharge conduit 52 is adapted to` extendthrough the housing 39 to an exhaustlopening 53 situated in the casingat the intermediate portion of the explosion chamber. Means, other thanthe main valve 43, are provided to introduce cooling air into theexplosion chamber along the length thereof. To this vend, a plurality ofports 54 are arranged in the casing 35 between each end of the chamber36 and the discharge conduit 52 to a'ord communication between theexplosion chamber 36 and the supply chamber 40.

The flow of air through the ports 54 is controlled bypressure'responsive valves 55, preferably in the form of reeds.Eachvalve is essentially a resilient member normally held seated overthe innerend 56v of its annular valve housing 51 by a boltf58 whichclamps one 'end portion of the valve 55 between a washer v59 and the end56 of the valve housing. Each-housing' 51 has a nice t in its port 54and is held fixedly' therein by bolts 63. Thus, whenever a hgherpressureexists in the supply chamber 40 than in the explosion chamber 36 thevalves 55 will bend inwardly in the direction of the explosion chamberand allow air to pass thereinto through the annular housing 51. To makethe valves readily accessible for replacement or' repair, ports 6I areprovided in the housing 39 opposite each of the ports 54 and said ports6l are normally covered by plates 62.

The length of the chamber 36 is so chosen and the frequency of theexplosions in the chamber is so timed that, when a pressure wave from anexplosion is at its peak in one end of the chamber, it willsimultaneously be at its lowest value in the other end of the chamberand, to this end, the length of the chamber approximates one half apressure Wave length or an odd multiple' thereof, Accordingly, in orderto determine the proper frequency of explosions for any given length ofthe chamber :i5-the natural frequency of the chamber being dependent onthe velocity at which the pressure wave travels in the chamber 36 andthe length of the chamber SS-it is merely necessary to vary the timingof the ignition and, of course, the injection of the fuel so that firingoccurs when the peak of a pressure Wave refiected from the opposite endof the chamber 35 reaches the explosion zone 43. When this timingrelationship exists, the pressure at the explosion end will be at amaximum Whereas the pressure at the opposite end of the container willbe substantially at a minimum and the frequency of explosions will thenbe equal to, or an odd multiple of, the natural frequency of thechamberV 36. Measurements of pressure at opposite ends of the containermay be facilitated by any Well known means (not shown). In furtheranceof this cycle of operation, an end plate 63 of the casing serves as areflecting inember to reverse the direction of movement of the peak ofthe pressure waves in the chamber 35 on contact therewith. The timing ofignition of the explosive charges in the zone 31 by the spark plug 48may be accomplished in any well known manner, such as illustrated inUnited States Patent 2,517,822.

At the beginning of an operating period of the plant, the starting motor33 imparts rotary movement to the rotors 24 and 25 causing compressedair to flow into the supply chamber 4Q and through the port 42/ into theexplosion zone 31. If then the fuel pump is put into operation, fuelwill be injected into the air in the explosion zone 31 through thenozzle 41' and the resulting explosive mixture will then be ignited bythe ,A

spark Vplug 48. This initial explosion forces the valve 43 to its seat,thereby cutting off the further flow of compressed air through the port42, and the pressure Wave of the explosion travels toward the oppositeend of the chamber 3B caus- ,u

ing a low pressure area to exist in front of the valve 43 which permitsthe valve to open and admit a new charge of air into the explosion zone31. As the trough of the wave passes over the valves 55 near 'theexplosion zone 31, they are forced open consecutively, starting withthose nearest the point of explosion, at the instant the pressure of thewave drops below that of the air in the supply chamber 49. Cooling airis thus admitted over a large area into the. explosion end of thechamber 36 to intermingle With the hot gasestherein. Y

When the peak of the pressure -vvave hits the end plate 63 'it isreflected back toward its point of origin but the trough of the originalwave will continue to move along toward the reflecting end of thechamber 35 and will thus also pass over thel valves 55 located near thereflecting end of the chamber 35 causing them to open consecutively andadmit additional cooling air from the supply chamber 40 into theexplosion chamber 36. The. cooling air also intermingles With theexplosion gases and reduces their temperature suitably for use in theturbine 2 l.

The peak of the reflected pressure Wave moving toward the explosion zone31 compresses the new charge of air therein and, at the instant when thepeak of the Wave reaches the explosion zone, fuel is injected throughthe nozzle 4l' into the compressed air and this explosive mixture isignited by the plug 48. Thus, another Wave is started which continuesthrough the same cycle as that just described but lags behind Ythepreceding Wave by approximately one wave length. n Y

ItV will be readily understood that the exhaust gases will pass from themiddle of the explosion chamber through the opening 53 at practically Ya constant pressure since the original pressure wave and its reflectedwave move simultaneously in opposite directions in the chamber and thereflected Wave originates at the instant the origi- Y the scope of theappended claims.

I claim: 1

1. A resonant explosion povverunit, comprising a casing forming anexplosion chamber, means for forming successive charges of an explosivemixture in only one end of the chamber, means for igniting the chargesof explosive mixture, .an -end member `on the casing approximatelyone-half of an explosion Wave length from the point of` explosion in thechamber for reversing the direction of movement of pressure Waves at theinstant of contact therewith, a plurality of valves arranged in spacedrelation along the length of the end portion of the explosion chamberadjacent the end member and acting responsively to the pressure wavestherein for introducing cooling air into the explosion gases, aplurality of valves arranged in spaced relation along the opposite endportion of the explosion chamber for admitting cooling air thereinto,and an exhaust opening in the casing intermediate the end member' andthe point oi' explosion. 2. A resonant explosion power unit, comprisinga casing having anv` explosion chamber having an explosion zone in onlyone end thereof, a housmg arranged around the casing to form an airsupply chamber therebetween, means for introducing the. air, 4and fuelconstituents Y or",

successive charges of Yan explosive mixture into the explosion chamber,means for igniting Vthe charges of explosive mixture at .a frequencyequal tothe natural frequency of the chamber, end members on the casingserving to 5 6 the exhaust gases at practically constant pres- FOREIGN"PATENTS sure from the explosion chamber. Number Country Date GEORGEFARNELL 1,329 Great Britain Jan. 24, 1905 27,724 Great Britain Dec. 16,1907 REFERENCES CITED 176,838 Great Britain Mar. 6, 1922 The followingreferences are of record inthe 188,642 vCirieatt Britain Nov. 29, 1923le of this patent: 239,434 Great Britain Sept. 10, 1925 UNITED STATESPATENTS 274,554 Great Britain Jan. 10, 1346 Number Name Date m 76,836Germany May 20, 1 33 332,313 Wilcox Dec. 15, 1885 2,480,626 Bodine Aug.30, 1949 2,523,379 `Kollsman Sept. 26, 1950 2,546,966 Bodine Apr. 3,1951 2,550,515 Anderson Apr. 24, 1951 15

